#include <iostream>
using namespace std;

void Duplicate(int *a, int *b, int *c) {
  *a *= 2;
  *b *= 2;
  *c *= 2;
}

int main () {
  int x = 1, y = 3, z = 7;
  Duplicate(&x, &y, &z);
  // The following outputs: x=2, y=6, z=14.
  cout << "x=" << x << ", y=" << y << ", z=" << z <<endl;
  return 0;
}
